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%I #13 Feb 04 2016 03:44:42
%S 1,3,7,5,-1,10,19,3,-2,10,15,18,5,7,32,8,-11,11,21,18,14,34,29,-1,-7,
%T -9,32,31,-2,37,51,16,-7,5,17,28,20,6,40,1,-15,41,49,32,14,45,50,7,
%U -28,-18,22,25,4,31,81,34,36,36,13,37,-12,11,58,8,-36,10,55
%N A117609(n)-A210639(n): Difference between number of lattice points in the ball x^2+y^2+z^2 <= n and the volume of this ball rounded to the nearest integer.
%C Record values are listed in A000223, and A000092 gives the corresponding indices. Strictly speaking, these are defined using the absolute values, but it appears they always occur at positive elements.
%t a[n_] := Sum[SquaresR[3, k], {k, 0, n}] - Round[(4/3)*Pi*n^(3/2)]; Table[a[n], {n, 0, 100}] (* _Jean-François Alcover_, Feb 04 2016 *)
%o (PARI) A210641(n)=A117609(n)-A210639(n)
%K sign
%O 0,2
%A _M. F. Hasler_, Mar 26 2012
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